Embodiments of the present disclosure relate to a semiconductor device, and more particularly to a semiconductor device that includes a gate electrode.
Generally, a semiconductor material has intermediate electrical conductivity between a conductor and a nonconductor. Although a semiconductor material acts as a nonconductor in a pure state, electrical conductivity of the semiconductor material is increased by introducing impurities into the semiconductor material through, e.g., ion implantation, diffusion, or the like. The semiconductor material is used to fabricate a semiconductor device such as a transistor. For example, the semiconductor device includes a semiconductor memory device.
A semiconductor memory device includes a plurality of transistors. The transistor has three regions, i.e., a gate, a source, and a drain. Electric charges move between the source and the drain through a channel region, according to a voltage level of a control signal input to the gate of the transistor.
As a semiconductor device is reduced in size, cell capacitance (Cs) is also reduced, which leads to decrease in a retention time. Since the cell capacitance (Cs) is reduced, although substantially the same bias is applied to the semiconductor device, an amount of charges stored in the semiconductor device may be reduced.